When (x – 2)^2 + 7 has a minimum value, what is the value of x?

First, expand (x-2)2:

= (x-2)(x-2),

= x2 - 2x - 2x + 4

= x2 - 4x + 4

Add on the +7:

= x2 - 4x + 11

complete the square

= (x - 2)2 - 4 + 11

= (x - 2)2 + 7

when the graph has a minumum value, (x - 2) = 0,

so x = 2

Tom L. avatar
Answered by Tom L. Maths tutor

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